of Bronzes from Machu Picchu, Peru. 587 



Object No. 7 (cf. Table I). 



That the Inca craftsmen were able to show considerable 

 variety in their methods of shaping these small implements 

 became evident on examination of the small knife with orna- 

 mental llama head at the extremity of the handle shown in fig. 

 15. A number of cast structures, some of them unaltered, 

 some altered by cold-working with annealing, and one altered 

 by hot-working, have been described. The present specimen 

 is of a duplex character, in that two distinct varieties of metal 

 were used in its construction. A vertical section sawed through 

 the center of the ornamental head and part of the shank is 

 shown diagrammatically in fig. 65. This diagram was made 

 from the polished, but unetched section, in which the boundary 

 line between the two kinds of metal was plainly apparent owing 

 to a difference of color and sharp discontinuity at the junction. 

 These facts are very well represented in the photo-micrograph, 

 fig. 66, taken at a magnification of 12 X from the unetched 

 section. The color difference is shown by the well developed 

 contrast between the two alloys, further accentuated by a den- 

 dritic structural resolution of the other alloy, which is mainly 

 due to a difference of hardness, and, consequently, of elevation 

 between the central cores and boundary zones of the branched 

 crystallites. The presence of numerous pits, or blow-holes, 

 located in the boundary zones where final solidification occurred 

 has also contributed to this effect. It is not necessary to resort 

 to etching, or to a higher magnification, in order to demonstrate 

 that the metal composing the main portion of the ornamental 

 head is now in the condition originally produced by casting. 

 This is evident from the casting structure revealed in fig. 66. 



When drillings were taken from this specimen for analysis, 

 its duplex character was not recognized and only the lower part 

 of the handle and the upper part of the blade were sampled. 

 This is the metal which projects up into the head and is of a 

 reddish tint, corresponding to its low tin-content of 3 per cent. 

 It is evident from the white color of the surrounding metal 

 that this contains a much higher percentage of tin. 



Fig. 67 represents the structure of the metal composing the 

 shank and blade of the knife. It is entirely homogeneous and 

 has been annealed after deformation. The grain count of 18 

 indicates that a temperature of 700-800° was reached in 

 annealing. 



Since the outside metal possesses a casting structure, it is 

 natural to conclude that it was cast in place around a core of 



